Currently, most semiconductor processing devices are single-wafer-devices processing type devices which process semiconductor wafers sheet by sheet. These single-wafer-processing type devices generally possess a susceptor inside a reaction chamber on which processing is performed while heating semiconductor wafers at a given temperature on the susceptor.
A typical susceptor in a single-wafer-processing type device comprises a disc-shaped body made of metal or ceramic having high heat conductivity, and has a built-in heating element such as an electric heater. This type of susceptor has at least three through-bores into which substrate-supporting pins are inserted vertically such that the pins can move freely. When an external transfer device carries a semiconductor wafer into the reaction chamber, the substrate-supporting pins extend upwards from the through-bores to receive the semiconductor wafer. The substrate-supporting pins then retract, setting the semiconductor wafer onto the susceptor.
When removing a processed semiconductor wafer from the reaction chamber, the substrate-supporting pins reextend from the through-bores, supporting the semiconductor wafer, whereupon the transfer device carries the semiconductor wafer out of the reaction chamber.
To extend and retract the substrate-supporting pins out of and into the through-bores of the susceptor, a horizontal support engaging the lower end of each substrate-supporting pin is provided immediately beneath the susceptor. This horizontal support is raised and lowered by a driving device such as an air cylinder.
The through-bores are typically provided on the inward side away from the periphery of a semiconductor wafer, and are blocked off from the processing environment by the semiconductor wafer during the semiconductor wafer processing.
In ultrafine and high-density semiconductor devices, particle contamination on the back of the semiconductor wafer is a problem. Conventional substrate-supporting pins directly contact the back of the semiconductor wafer. Particles often adhere to the back of the wafer at these points of contact.
The head of the wafer-supporting pin may be tapered to block-off the through-bore of the susceptor. Because the wafer-supporting pin is seated solely by its own weight, the pin may bind and not properly seat.
If the wafer-supporting pin is situated at the periphery of the semiconductor wafer, a step in the head of the wafer-supporting pin must be provided to hold the edge of the semiconductor wafer, necessitating a whirl-stop.